Car owners in the United
States last year bought more than 96,000 plug-in electric cars, a year-on-year
increase of 84 percent from 2012. However, this growing fleet will put a lot
of new strain on the nation’s aging electrical distribution systems, like
transformers and underground cables, especially at times of peak demand — in
the evening when people come home from work.

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How to manage all these
cars seeking a socket at the same time — without crashing the grid or pushing
rates to the roof — has some utilities wondering, if not downright worried.

Now a team of University of
Vermont scientists has created a novel solution.

"The key to our approach is
to break up the request for power from each car into multiple small chunks —
into packets," says Jeff Frolik, a professor in the College of Engineering and
Mathematical Sciences and co-author on the new study.

By using the nation's
growing network of "smart meters" — a new generation of household electric
meters that communicate information back-and-forth between a house and the
utility — the new approach would let a car charge for 5 or 10 minutes at a
time. And then the car would "get back into the line," Frolik says, and make
another request for power. If demand was low, it would continue charging, but
if it was high, the car would have to wait.

"The vehicle doesn't care.
And, most of the time, as long as people get charged by morning, they won't
care either," says UVM's Paul Hines, an expert on power systems and co-author
on the study. "By charging cars in this way, it's really easy to let everybody
share the capacity that is available on the grid."

Taking a page out of how
radio and internet communications are distributed, the team's strategy will
allow electric utilities to spread out the demand from plug-in cars over the
whole day and night. The information from the smart meter prevents the grid
from being overloaded. "And the problem of peaks and valleys is becoming
more pronounced as we get more intermittent power — wind and solar — in the
system," says Hines. "There is a growing need to smooth out supply and demand."

At the same time, the UVM
teams' invention — patent pending — would protect a car owner's privacy. A
charge management device could be located at the level of, for example, a
neighborhood substation. It would assess local strain on the grid. If demand weren't
too high, it would randomly distribute "charge-packets" of power to those
households that were putting in requests.